The need to educate deaf students in their own language, sign language, is well recognized and is widely accepted as being a positive influence on learning. Researchers, technologists and teaching organizations aim to develop new learning technologies that support sign language education. Kids Sign Online (KSO) is an adaptive WWW-based system, specifically designed to teach British Sign Language in tandem with English to deaf children. KSO is unique in that it is an advanced learning technology that utilizes adaptive strategies together with digital video, presented by deaf children, for deaf children, to facilitate learning. The system has been designed and built in consultation with the British Deaf Association, and has been empirically tested with broadly positive results.